[lib] extend defaultEmojiAvatars

Summary: extend the defaultEmojiAvatars based off this list from Ted. As I was building the list I made sure that the emoji and background color had good contrast (a yellow emoji didn't have a yellow background)

Test Plan: I could see the new default emoji avatars rendered

Reviewers: ashoat, atul

Reviewed By: ashoat

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D7582